router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in on one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it gets to its destination node.

1. what is Cloud Computing?

Cloud computing refers to the delivery of computing and storage capacity[citation needed] as a service[citation needed] to a heterogeneous community of end-recipients. The name comes from the use of clouds[citation needed] as an abstraction for the complex infrastructure it contains in system diagrams[citation needed]. Cloud computing entrusts services with a user's data, software and computation over a network. It has considerable overlap with software as a service (SaaS).

2.From where we can purchase device?

You can go to here for purchasing device

3. What is a gateway or Router?

A node that is connected to two or more networks is commonly called as router or Gateway. It generally forwards message from one network to another.

4. When a switch is said to be congested?

It is possible that a switch receives packets faster than the shared link can accommodate and stores in its memory, for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped and in this state is said to congested state.

5. What are the types of errors?

a. Single-Bit error In a single-bit error, only one bit in the data unit has changed b. Burst Error A Burst error means that two or more bits in the data have changed.

6.What is VRC?

t is the most common and least expensive mechanism for Error Detection. In VRC, a parity bit is added to every data unit so that the total number of 1s becomes even for even parity. It can detect all single-bit errors. It can detect burst errors only if the total number of errors in each data unit is odd.

7.Define Retransmission?

Retransmission is a technique in which the receiver detects the occurrence of an error and asks the sender to resend the message. Resending is repeated until a message arrives that the receiver believes is error-freed.